1. Field of the Invention
This invention relates to new compounds containing aminophenoxy end groups, to a process for their preparation and to their use as starting components for the production of cellular or non-cellular polyurethane plastics and foams.
2. Description of the Prior Art
Polyadducts containing aromatic amino end groups are basically already known. U.S. Pat. No. 2,888,439 and DE-OS 17 20 646 describe the preparation of amino polyethers by the reaction of nitroarylisocyanates with polyols followed by hydrogenation. The analogous reaction of azoaryl isocyanates with polyols also yields aromatic aminopolyethers after reduction (DE-OS 12 57 427). A process in which isocyanate prepolymers are reacted with diamines containing different reactive amino groups is described in DE-OS 11 22 254 and DE-OS 16 94 152. The reaction of isocyanate prepolymers with sulphamic acid according to DE-AS 11 55 907, with formic acid according to FR-PS 14 15 317 or with enamines, aldimines or ketimines containing hydroxyl groups according to DE-OS 21 16 882 and DE-OS 25 46 536 results in aromatic amino polyethers after hydrolysis and saponification as does the thermal splitting of urethanes from isocyanate prepolymers and secondary or tertiary carbinols according to DE-AS 12 70 046. DE-OS 29 48 419, 32 23 397, 32 23 398 and 32 23 400 describe various single stage and two-stage processes for the preparation of aromatic polyamines by the hydrolysis of isocyanate prepolymers in the presence of various solvent and catalyst systems.
All the processes hitherto described take place via isocyanate intermediate stages and therefore invariably yield products containing urethane or urea groups in addition to ether and aromatic amino groups. These products therefore have an undesirably high viscosity for many purposes. Another disadvantage of these additional urethane and urea bonds is their relatively low thermal stability which adversely affects the heat resistance of polyurethane plastics, particularly elastomers, produced from these amino polyethers.
Another possible method for the synthesis of aromatic polyamines is the reaction of isatoic acid anhydride with polyols accompanied by ring opening. Amines of this type are described, for example, in DE-OS 20 19 432, 26 19 840, 26 48 774 and 26 48 825 and in U.S. Pat. No. 4,180,644. Aromatic amino polyethers are also obtained by the reaction of polyoxyalkylene polyols with p-aminobenzoic acid derivatives according to Japanese Patent applications 59 053 533, 59 089 322 and 59 199 715. One disadvantage for many purposes, however, is the low reactivity of the aromatic ester amines obtained by this method.
It was therefore an object of the present invention to provide new aromatic polyamines which would not have the disadvantages mentioned above and would in particular have lower viscosities and react more advantageously with isocyanates. This problem was solved by providing the new compounds containing aminophenoxy end groups and the process described below for their preparation.